inverse of y = x2 – 10x.?????????

2 Answers

• This isn’t easy. First, there are multiple values of x for the same value of y, so there isn’t a proper inverse function on the whole domain. Here’s how you do it:

  y = x^2 – 10x + 25 – 25

  y = (x-5)^2 – 25

  y+25 = (x-5)^2

  x-5 = +/-sqrt(y+25)

  And you get TWO inverses:

  x = 5 + sqrt(y+25), for x>=5

  x = 5 – sqrt(y+25), for x<=5

  Hope this helped!

• I’m no expert but I’m pretty sure it’s just over 1.

  so

  y = x2 – 10x

  y[inverse] = (1) / (x2 – 10x)